Orbital forging device, method for orbital forging, method for manufacturing hub unit bearing using method for orbital forging, and method for manufacturing vehicle

ABSTRACT

Provided is construction which is able to downsize an orbital forging device comprising a spherical seat with shaft that swings and rotates with a molding die. The end section on the other side in the axial direction of the swinging shaft 13 is supported with respect to the driving mechanism 17 in a state where the movement toward one side in the axial direction (lower side) is prevented, and a member for preventing the swinging shaft 13 from moving toward the one side in the axial direction with respect to the frame 10 is not assembled in a section which is located between the convex spherical seat 14 and the driving mechanism 17 in the axial direction of the swinging shaft 13.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.16/490,305, filed on Aug. 30, 2019, which is a U.S. National Stage ofApplication No. PCT/JP2018/007486, filed on Feb. 28, 2018, which claimspriority from Japanese Patent Application No. 2017-038933, filed on Mar.2, 2017, the disclosures of which are incorporated herein by referencein their entirety.

TECHNICAL FIELD

The present invention relates to an orbital forging device and a methodfor orbital forging which are used for forming a crimped portion byplastically deforming a cylindrical section provided in an end sectionin the axial direction of a shaft member such as a hub outward in theradial direction. The present invention also relates to a method formanufacturing a hub unit bearing using this method for orbital forging,and a method for manufacturing a vehicle using this method formanufacturing a hub unit bearing.

BACKGROUND ART

In vehicles such as automobiles, wheels are rotatably supported to asuspension respectively by a hub unit bearing such as illustrated inFIG. 4.

The hub unit bearing illustrated in FIG. 4 comprises an outer ring 1that does not rotate in use with connected and fastened to a suspension,a hub 2 that rotates in use with a wheel supported and fixed thereto,and balls 5 as a plurality of rolling elements that are rollablyprovided between double-row outer ring raceways 3 a, 3 b provided on theinner circumferential surface of the outer ring 1 and double-row innerring raceways 4 a, 4 b provided on the outer circumferential surface ofthe hub 2.

The hub 2 is constructed by connecting and fastening a hub body 6 inwhich the inner ring raceway 4 a on the outside (left side in FIG. 4) inthe axial direction is formed on the outer circumferential surface andan inner ring 7 in which the inner ring raceway 4 b on the inside (rightside in FIG. 4) in the axial direction is formed on the outercircumferential surface. The hub 2 corresponds to a shaft member. Morespecifically, in a state where the inner ring 7 is externally fittedonto the section near the inner end in the axial direction of the hubbody 6, the inner end section in the axial direction of the cylindricalsection 8 which is provided in the inner end section in the axialdirection of the hub body 6 is plastically deformed outward in theradial direction so as to form a crimped portion 9, and the hub 2 isconstructed by pressing the inner end surface in the axial direction ofthe inner ring forcefully by the crimped portion 9. In the hub unitbearing, the outside in the axial direction or the inside in the axialdirection means outside in the width direction or inside in the widthdirection of a vehicle in a state where the hub unit bearing is mountedin a vehicle.

In vehicles having relatively light weight such as automobiles, it iscommon that wheels are supported to a vehicle by a hub unit bearingusing balls 5 as rolling elements. However, in heavy vehicles such astrucks, as disclosed in JP2000-343905(A) and JP2003-083353(A) andillustrated in FIG. 5, wheels are supported to a vehicle by a hub unitusing tapered rollers 5 a as rolling elements.

The crimped portion 9 is, for example, formed by orbital forging. Inthis case, for example, as illustrated in FIG. 6, in a state where thecenter axis ß of the molding die 15 is inclined to a predetermined angleθ (for example, about 1 degree to 5 degrees) with respect to the centeraxis α of the hub body 6, the molding die 15 is pressed to the inner endsection in the axial direction of the cylindrical section 8. In thisstate, the molding die 15 is made to swing and rotate (i.e. revolve)around the center axis α of the hub body 6. When doing this, the moldingdie 15 rotates around its center axis ß based on the friction force thatacts on the contact portion thereof with the inner end section in theaxial direction of the cylindrical section. Due to this, by applyingaxial outward and radial outward load to a portion in thecircumferential direction of the cylindrical section 8 as well as bycontinuously changing the portion where this load has been applied inrelation to the circumferential direction, as illustrated in FIG. 6, theinner end section in the axial direction of the cylindrical section 8 isplastically deformed gradually so as to form a crimped portion 9.

In the hub unit bearing comprising in which the hub 2 is formed bypressing down the inner end section in the axial direction of the innerring 7 with the crimped portion 9, in order to prevent creep between thehub body 6 and the inner ring 7, the force to press down the inner endsection in the axial direction of the inner ring 7 with the crimpedportion 9 is required to be large. However, when the inclination angle θof the center axis ß of the molding die 15 with respect to the centeraxis α of the hub body 6 is small like 5 degrees or less, machining loadfor forming the crimped portion 9 becomes large, so it becomes difficultto adjust the force to press down the inner end section in the axialdirection of the inner ring 7 with the crimped portion 9. When the forcefor pressing down the inner end section in the axial direction of theinner ring 7 with the crimped portion 9 becomes excessively large, theremay be a case where the inner ring 7 plastically deforms as if the innerring raceway 4 b on the inside in the axial direction provided on theouter circumferential surface expands. When the inner ring 7 plasticallydeforms, problems arise such as the preload that is given to the rollingelements become unstable. Especially, the effect due to the plasticdeformation of the inner ring 7 is remarkable in the hub unit bearingusing tapered rollers 5 a as rolling elements as illustrated in FIG. 5.

As a device for performing such orbital forging, JP2013-091067(A) andJP2015-077616(A) disclose an orbital forging device comprising aspherical seat with shaft. FIG. 7 illustrates an example of an orbitalforging device disclosed in JP2013-091067(A), the orbital forging devicecomprising a connected body 23 of a spherical seat with shaft 12 and amolding die 15.

The spherical seat with shaft 12 comprises a swinging shaft 13 and aconvex spherical seat 14 that is integrally formed so as to be coaxialwith the swinging shaft 13 at the end section on one side in the axialdirection (lower end portion in FIG. 7) of the swinging shaft 13. Of theconvex spherical seat 14 of the spherical seat with shaft 12, on oneside section in the axial direction of the swinging shaft 13, themolding die 15 is held and fixed to so as to be coaxial with theswinging shaft 13. The other side section in the axial direction of theswinging shaft 13 of the convex spherical seat 14 (upper side portion inFIG. 7) spherically engages with the concave spherical seat 16 that isfixed to the frame of the orbital forging device.

The end section on the other side in the axial direction of the swingingshaft 13 of the spherical seat with shaft 12 is connected to a drivingmechanism that is assembled in the frame of the orbital forging devicevia a rolling bearing 28 of this driving mechanism. Further, a thrustsliding bearing 42 having a partially spherical sliding surface isassembled between the intermediate section in the axial direction of theswinging shaft 13 and the frame (concave spherical seat 16).

In such an orbital forging device, driving force for swinging androtating the spherical seat with shaft 12 and the molding die 15 isgiven from the driving mechanism to the end section on the other side inthe axial direction of the swinging shaft 13. Further, due to thespherical engagement between the convex spherical seat 14 and theconcave spherical seat 16, swing and rotation of the spherical seat withshaft 12 and the molding die 15 are allowed and processing reactionforce applied to molding die 15 is supported. Further, swing androtation of the spherical seat with shaft 12 and the molding die 15 isallowed by the thrust sliding bearing 42, and the spherical seat withshaft 12 and the molding die 15 are prevented from moving to the oneside in the axial direction of the swinging shaft 13 with respect to theframe (the driving mechanism and the concave spherical seat 16), thatis, dropping from the orbital forging device.

In the conventional orbital forging device, the connecting sectionbetween the end section on the other side in the axial direction of theswinging shaft 13 and the driving mechanism does not have a functionthat prevents the spherical seat with shaft 12 and the molding die 15from moving to the one side in the axial direction of the swinging shaft13 with respect to the frame (the driving mechanism and the concavespherical seat 16), instead the thrust sliding bearing 42 has thisfunction.

PRIOR ART DOCUMENTS Patent Literature [Patent Literature 1]JP2000-343905 (A) [Patent Literature 2] JP2003-083353 (A) [PatentLiterature 3] JP2013-091067 (A) [Patent Literature 4] JP2015-077616 (A)SUMMARY OF INVENTION Problem to be Solved by Invention

In the conventional orbital forging device, a thrust sliding bearing 42having a partially spherical sliding surface is assembled between theintermediate section in the axial direction of the swinging shaft 13 andthe frame (concave spherical seat 16). Therefore, it is required tosecure installation space for this thrust sliding bearing 42 and thusthe size of the orbital forging device becomes larger. Further, thepartially spherical sliding surface of the thrust sliding bearing 42 isrequired to be formed highly precisely, so the cost for manufacturing anorbital forging device becomes higher.

Further, when forming the crimped portion 9 of the hub unit bearing byorbital forging, the swing angle of the molding die 15 (inclinationangle θ of the center axis ß of the molding die 15 with respect to thecenter axis α of the hub body 6) is thought to be preferable to be setat 15 degrees or more and 30 degrees or less from the view point ofsuppressing deformation of the inner ring 7 when forming the crimpedportion 9 and suppressing the maximum machining load at low level so asto make the size of the orbital forging device smaller (seeJP2015-077616(A)). However, in the conventional orbital forging device,if the swing angle θ of the molding die 15 is set to be 15 degrees ormore, the outer diameter dimension of the thrust sliding bearing 42becomes larger as well, so problems such as increasing in size andmanufacturing cost become remarkable.

Taking into consideration the problems described above, the object ofthe present invention is to provide construction which is able to setthe swing angle of the molding die to be large at 15 degrees or more and30 degrees or less and to reduce size of an orbital forging device aswell as its manufacturing cost for the orbital forging device comprisinga spherical seat with shaft that swings and rotates with a molding die.

Means for Solving Problems

The orbital forging device of the present invention comprises a frame, aswinging shaft, a convex spherical seat, a molding die, a concavespherical seat, and a driving mechanism.

The frame has a reference axis.

The swinging shaft comprises a center axis, an end section on one sidein the axial direction, and an end section on the other side in theaxial direction, and the center axis is arranged so as to be inclined tothe reference axis.

The convex spherical seat comprises one side section in the axialdirection of the swinging shaft, the other side section in the axialdirection of the swinging shaft, and a convex spherical surface sectionprovided on the other side section, and is connected at the end sectionon the one side section in the axial direction of the swinging shaft soas to be coaxial with the swinging shaft.

The molding die comprises a machining surface section in a side surfaceon the one side in the axial direction of the swinging shaft, and isconnected to the one side section of the convex spherical seat so as tobe coaxial with the swinging shaft.

The concave spherical seat is fixed to the frame and comprises a concavespherical surface section that spherically engages with the convexspherical surface section and an insertion hole to which the swingingshaft is inserted.

The driving mechanism is assembled in the frame and is connected to theend section on the other side in the axial direction of the swingingshaft so as to provide driving force for rotating a connected body ofthe swinging shaft, the convex spherical seat, and the molding diearound the reference axis to the end section on the other side in theaxial direction of the swinging shaft.

Especially, in the orbital forging device of the present invention, theend section on the other side in the axial direction of the swingingshaft is supported to the driving mechanism in a state where a movementthereof toward the one side in the axial direction is prevented.

In the present invention, for example, it is possible to employconstruction where the driving mechanism comprises a rotating body whichis supported to the frame so as to be able to rotate around thereference axis, a retention hole which is provided in the rotating bodyand to which the end section on the other side in the axial direction ofthe swinging shaft is inserted, and a rolling bearing which is providedbetween the retention hole and the end section on the other side in theaxial direction of the swinging shaft, and the end section on the otherside in the axial direction of the swinging shaft is supported to therotating body by the rolling bearing in a state where a movement thereoftoward the one side in the axial direction is prevented.

In the present invention, for example, it is possible to employconstruction where the rolling bearing comprises an outer ring, an innerring, and a plurality of rolling elements located between the outer ringand the inner ring, and is able to support axial load that acts onbetween the outer ring and the inner ring, and the inner ring isexternally fitted onto the end section on the other side in the axialdirection of the swinging shaft in a state where a displacement thereofto the other side in the axial direction of the swinging shaft isprevented, and the outer ring is fitted inside the retention hole in astate where a displacement thereof to the one side in the axialdirection of the swinging shaft is prevented.

In the present invention, for example, it is possible to employconstruction in which the rotating body has a case member supported tothe frame so as to be able to rotate around the reference axis, and abearing holder having the retention hole, and the bearing holder isdetachably fixed to the case member.

In the present invention, for example, it is possible to employconstruction which further comprises a holding member which isdetachably fixed to the case member in addition to the case member andthe bearing holder.

In this case, the case member comprises a bottomed holding recesssection that opens in a side surface opposite to the molding die withrespect to a direction of the reference axis and a through-hole which isformed in a part of a section that corresponds to a bottom section ofthe holding recess section.

The bearing holder further comprises an outer circumferential surface,and a first inclined surface section that is formed in a portion in thecircumferential direction of the outer circumferential surface and isinclined in a direction toward the retention hole with respect to adirection that is perpendicular to the reference axis toward an oppositeside to the molding die with respect to the direction of the referenceaxis.

The holding member comprises an outer circumferential surface and asecond inclined surface section that is formed in a part in thecircumferential direction of the outer circumferential surface and isable to make a surface contact with the first inclined surface section.

The bearing holder and the holding member are fitted inside the holdingrecess section in a state where the first inclined surface section andthe second inclined surface section come in contact, and preload in adirection toward a bottom section side of the holding recess section isapplied to the holding member.

The end section on the other side in the axial direction of the swingingshaft is inserted to the through-hole of the case member and theretention hole of the bearing holder.

In the present invention, the inclination angle of the center axis ofswinging shaft with respect to the reference axis can be 15 degrees ormore and 30 degrees or less.

The method for orbital forging of the present invention comprises a stepof plastically deforming a cylindrical section provided in an endsection in an axial direction of a shaft member outward in a radialdirection thereof to form a crimped portion, in which, using the orbitalforging device of the present invention, the molding die is pressed tothe end section in the axial direction of the cylindrical section of theshaft member in a state where the center axis of the molding die isinclined to the center axis of the shaft member to a predeterminedangle.

The inclination angle of the center axis of the molding die with respectto the center axis of the shaft member can be set to be 15 degrees ormore and 30 degrees or less.

In a method for manufacturing a hub unit bearing of the presentinvention,

the hub unit bearing comprises:

an outer ring that does not rotate in use with connected and fastened toa suspension, a hub that rotates together with a wheel in use with thewheel supported and fastened thereto, and a plurality of rollingelements that are rollingly arranged between double-row outer ringraceways provided on an inner circumferential surface of the outer ringand double-row inner ring raceways provided on an outer circumferentialsurface of the hub, and the hub comprises a hub body having an innerring raceway on an outside in the axial direction of the double-rowinner ring raceways on an outer circumferential surface thereof, and aninner ring having an inner ring raceway on an inside in the axialdirection of the double-row inner ring raceways on an outercircumferential surface thereof, the hub body and the inner ringfastened and fixed to each other, and

the method comprises a step of plastically deforming an inner endsection in the axial direction of a cylindrical section provided on aninner end section in the axial direction of the hub body outward in theradial direction with the inner ring externally fitted onto a sectionnear an inner end in the axial direction of the hub body using theorbital forging device of the present invention to form a crimpedportion and to make the crimped portion press down an inner end surfacein the axial direction of the inner ring.

In a method for manufacturing a vehicle of the present invention,

the vehicle has a structure in which a wheel is rotatably supported to asuspension of the vehicle by a hub unit bearing, and

the method comprises a step of manufacturing the hub unit bearing byusing the method for manufacturing the hub unit bearing of the presentinvention.

Effect of Invention

In the orbital forging device and the method for orbital forging usingthe orbital forging device of the present invention, the end section onthe other side in the axial direction of the swinging shaft is supportedto the driving mechanism in a state where the movement thereof towardthe one side in the axial direction is prevented. Therefore, due to thissupporting section, the connected body of the swinging shaft, the convexspherical seat, and the molding die is prevented from moving toward theone side in the axial direction with respect to the frame.

Further, a member for preventing the swinging shaft from moving towardthe one side in the axial direction with respect to the frame, forexample, a thrust sliding bearing having a partially spherical slidingsurface, is not assembled in a section of the swinging shaft that islocated between the convex spherical seat and the driving mechanism withrespect to the axial direction.

Therefore, the swing angle of the molding die which is an inclinationangle of the swinging shaft with respect to the reference axis can beset to be large at 15 degrees or more and 30 degrees or less, and it ispossible to reduce the size of the device and its manufacturing cost.

Further, in the orbital forging device and the method for orbitalforging using the orbital forging device of the present invention, whenthe rotating body of the driving mechanism comprises a case member, anda bearing holder (or a bearing holder and a holding member) which is(are) detachably fixed to the case member, by changing the inclinationangle of the retention hole with respect to the reference axis byexchanging the bearing holder (or the bearing holder and the holdingmember), it is possible to change the swing angle of the molding die,which is an inclination angle of the swinging shaft with respect to thereference axis, in a wide range.

Further, in a method for manufacturing a hub unit bearing and in amethod for manufacturing a vehicle including a process of manufacturinga hub unit bearing using this method for manufacturing a hub unitbearing, by employing the orbital forging device and the method fororbital forging of the present invention, it is made possible tomanufacture a hub unit in which the deformation of the inner ring issuppressed and to make the device compact and reduce manufacturing costthereof.

Therefore, the industrial significance of the present invention is verylarge.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating the orbitalforging device of an example of an embodiment of the present invention.

FIG. 2(a) is a cross-sectional view which specifically illustrates partof the rotating body of the driving mechanism of the orbital forgingdevice illustrated in FIG. 1.

FIG. 2(b) is a plan view which specifically illustrates parts of therotating body of the driving mechanism of the orbital forging deviceillustrated in FIG. 1.

FIGS. 3(a) and 3(b) are an enlarged cross-sectional views of a mainsection illustrating the processes for forming the crimped portion ofthe hub unit bearing by the orbital forging device illustrated in FIG. 1in order.

FIG. 4 is a cross-sectional view illustrating an example of aconventionally known hub unit bearing.

FIG. 5 is a cross-sectional view illustrating another example of aconventionally known hub unit bearing.

FIG. 6 is a cross-sectional view illustrating a process for forming acrimped portion of the hub unit bearing by a conventionally knownorbital forging device.

FIG. 7 is a cross-sectional view illustrating an example of a connectedbody of the spherical seat with shaft and the molding die of aconventionally known orbital forging device.

MODES FOR CARRYING OUT INVENTION

An example of an embodiment of the present invention will be explainedwith reference to FIG. 1 to FIG. 5. The orbital forging device of thepresent example is used for forming a crimped portion 9 of the hub unitbearing illustrated in FIG. 4 or FIG. 5. This orbital forging devicecomprises a frame 10, an elevating base 11, a spherical seat with shaft12 (provided with a swinging shaft 13 and a convex spherical seat 14), amolding die 15, a concave spherical seat 16, and a driving mechanism 17.

The frame 10 is placed on a floor of a factory and the like. The frame10 has a reference axis α in the vertical direction. In other words, thereference axis α is set in the vertical direction of the frame 10.

The elevating base 11 is located at the lower section in the frame 10 soas to be able to move up and down along the reference axis a. To theelevating base 11, a hydraulic mechanism (not shown) for driving thiselevating base 11 up and down is connected. A support jig 18 forsupporting the hub body 6, which is a work piece, without rattle inrelation to the radial direction is provided at the top surface of theelevating base 11.

The spherical seat with shaft 12 comprises a swinging shaft 13 which hasa center axis ß and extends along the center axis ß, and a convexspherical seat 14 which is connected to the swinging shaft 13 so as tobe coaxial with the swinging shaft 13 at the end section on one side inthe axial direction (the lower end section in FIG. 1). The sphericalseat with shaft 12 is arranged above the elevating base 11 in the framein a state where the center axis ß is tilted at a predetermined angle θto the reference axis α. The convex spherical seat 14 is connected tothe swinging shaft 13 on the other side section in the axial direction(the upper side section in FIG. 1) of the swinging shaft 13. The otherside section in the axial direction of the swinging shaft 13 of theconvex spherical seat 14 is, except for the section which is connectedto the swinging shaft 13 of the convex spherical seat 14, composed of aconvex spherical surface section 19. The center of curvature of theconvex spherical surface section 19 exists on the center axis ß of theswinging shaft 13. Therefore, the swinging shaft 13 and the convexspherical seat 14 are arranged coaxially. Such spherical seat with shaft12 may be formed so as to be integral as a whole, or formed by combiningplural parts.

The molding die 15 is connected to one side section of the convexspherical seat 14 in the axial direction of the swinging shaft 13 so asto be coaxial with the swinging shaft 13. The side surface of themolding die 15 on one side with relation to the axial direction of theswinging shaft 13 comprises a machining surface section 20 which isannular and coaxial with the center axis ß of the swinging shaft 13.Such molding die 15 may be formed so as to be separate from thespherical seat with shaft 12, or may be formed so as to be integral withthe entire spherical seat with shaft 12 or to be integral with someparts of the spherical seat with shaft

The concave spherical seat 16 is fixed to the intermediate section inthe vertical direction of the frame 10. This concave spherical seat 16comprises a concave spherical surface section 22 that sphericallyengages with the convex spherical surface section 19 of the convexspherical seat 14 and an insertion hole 21 to which the end section onthe one side in the axial direction of the swinging shaft 13 isinserted. The center of curvature of the concave spherical surfacesection 22 exists on the reference axis α. Such concave spherical seat16 allows the connected body 23 of the molding die 15 and the sphericalseat with shaft 12 swing and rotate (i.e. revolve) around the referenceaxis α based on making the convex spherical surface section 19spherically engage with the concave spherical surface section 22, andallows the connected body 23 rotates around the center axis ß, as wellas support machining reaction force that is applied to the molding die15 when performing orbital forging.

In the present example, the insertion hole 21 of the concave sphericalseat 16 is composed of a tapered hole having an inner diameter dimensionthat becomes larger toward the above. Further, a portion of the innercircumferential surface of the frame 10 which is adjacent above theinsertion hole 21 of the concave spherical seat 16 and to which theintermediate section in the axial direction of the swinging shaft 13 isinserted, is composed of a stepped hole 24 having an inner diameterdimension that becomes larger step by step toward the above. The innerdiameter dimension of these insertion hole 21 and the stepped hole 24is, as described above, set to be as small as possible within a rangethat the connected body 23 of the molding die 15 and the spherical seatwith shaft 12 does not interfere with the swinging shaft 13 when theconnected body 23 swings and rotates around the reference axis α. In thepresent example, the reason why the portion of the inner circumferentialsurface of the frame 10 which is adjacent above the insertion hole 21 ismade as the stepped hole 24 is due to easiness of processing when usinggeneral processing equipment. When embodying the present invention, ifit is possible to process, the stepped hole 24 may be changed to atapered hole having an inner diameter dimension that becomes largertoward the above.

The driving mechanism 17 is assembled in the upper end section in theframe 10. The end section on the other side in the axial direction ofthe swinging shaft 13 that protrudes upwards from the stepped hole 24 isconnected to the driving mechanism 17. The driving mechanism 17 givesdriving force to the end section on the other side in the axialdirection of the swinging shaft 13 so as to make the connected body 23of the molding die 15 and the spherical seat with shaft 12 swing androtate around the reference axis α.

The driving mechanism 17 comprises a rotating body 26, a retention hole27, and a rolling bearing 28.

The rotating body 26 is supported inside the upper end section of theframe 10 by a bearing device 25 so as to be able to rotate only aroundthe reference axis α. An output section of a motor (not shown) forrotating and driving the rotating body 26 is connected directly or via areducer (not shown).

The retention hole 27 is provided in a part in the circumferentialdirection of the intermediate section in the radial direction of therotating body 26. The center axis of the retention hole 27 is inclinedby substantially the same angle as the inclination angle θ with respectto the reference axis α.

The rolling bearing 28 is arranged between the inner circumferentialsurface of the retention hole 27 and the outer circumferential surfaceof the end section on the other side in the axial direction of theswinging shaft 13, and supports the end section on the other side in theaxial direction of the swinging shaft 13 with respect to the retentionhole 27 so as to be able to rotate freely.

Especially, in the present example, due to the rolling bearing 28, theend section on the other side in the axial direction of the swingingshaft 13 is supported to the driving mechanism 17 in a state where themovement toward the one side in the axial direction (drop downward inFIG. 1).

In order to be responsible for the function of preventing the rollingbearing 28 from moving toward the one side in the axial direction, therolling bearing 28 comprises construction having bearing capacity foraxial load in addition to bearing capacity for radial load. Inparticular, as the rolling bearing 28, a self-aligning roller bearing isused. In this self-aligning roller bearing, a plurality of sphericalrollers 31 are rollingly arranged between the inner circumferentialsurface of the outer ring 29 and the outer circumferential surface ofthe inner ring 30, and the attitude and the locations of these pluralityof spherical rollers 31 are controlled by a cage (not shown). Due tosuch construction, the rolling bearing 28 can support the radial loadthat acts on between the outer ring 29 and the inner ring 30 as well asthe axial load that acts on between the outer ring 29 and the inner ring30. Further, even if the center axes of the outer ring 29 and the innerring 30 are slightly inclined to each other, the rolling bearing 28 hasautomatic alignment such as to be able to make the rolling of thespherical rollers 31 between the outer ring 29 and the inner ring 30smooth. Specific construction of such a self-aligning roller bearing isalready known, so its explanation is omitted. When embodying the presentinvention, as the rolling bearing 28, it is possible to use bearingssuch as a deep groove ball bearings and an angular ball bearing.

The outer ring 29 is fitted inside the retention hole 27 in a statewhere it is prevented to move toward the one side in the axial directionof the swinging shaft 13. For that, the inner circumferential surface ofthe retention hole 27 is composed of a stepped hole having a steppedsurface 32 facing toward the other side in the axial direction (theupper side in FIG. 1) in the intermediate section in the axialdirection. The outer ring 29 is fitted inside a section of the retentionhole 27 which locates on the other side in the axial direction than thestepped surface 32 without rattle, and the end surface on the one sidein the axial direction of the outer ring 29 comes in contact with thestepped surface 32.

The inner ring 30 is externally fitted onto the end section on the otherside in the axial direction of the swinging shaft 13 in a state where itis prevented to move toward the other side in the axial direction of theswinging shaft 13. Therefore, the inner ring 30 is externally fittedonto the end section on the other side in the axial direction of theswinging shaft 13 without rattle, and a nut 34 is screwed and fixed to amale screw section 33 which is provided at the end section on the otherside in the axial direction of the swinging shaft 13, and this nut 34comes in contact with the end surface on the other side in the axialdirection of the inner ring 30.

Due to such construction, it is prevented that the end section on theother side in the axial direction of the swinging shaft 13 moves towardthe one side in the axial direction with respect to the drivingmechanism 17, that is, the connected body 23 is prevented from droppingdownwards from the orbital forging device.

In the present example, by adjusting the screwing position of the nut 34with respect to the male screw section 33 so as to adjust the spacebetween the nut 34 and the convex spherical seat 14, in a state wherethe machining surface section 20 of the molding die 15 is before pressedto the cylindrical section 8 of the hub body 6, or, in a state where themachining surface section 20 is pressed to the cylindrical section 8,the size of the gap (engagement allowance) which exists in the sphericalengagement section between the convex spherical surface section 19 andthe concave spherical surface section 22 is optimized.

In the present invention, alternative to construction where the nut 34is screwed and fixed to the male screw section 33, for example, it ispossible to employ construction where the inner ring is externallyfitted onto the end section on the other side in the axial direction ofthe swinging shaft, or construction where a retaining ring which islocked to the end section on the other side in the axial direction ofthe swinging shaft comes in contact with the end surface of the otherside in the axial direction of the swinging shaft of both end surfacesin the axial direction of the inner ring so as to prevent the inner ringwhich is externally fitted onto the end section on the other side in theaxial direction of the swinging shaft from moving toward the other sidein the axial direction of the swinging shaft.

Further, alternative to the construction where the end surface on theone side in the axial direction of the outer ring 29 comes in contactwith the stepped surface 32, for example, it is possible to employconstruction where the outer ring is fitted inside the retention holewith interference fit, or construction where a nut which is screwed andfixed to the retention hole or a retaining ring which is locked to theretention hole comes in contact with the end surface of the one side inthe axial direction of the swinging shaft of both end surfaces in theaxial direction of the outer ring so as to prevent the outer ring whichis fitted inside the retention hole from moving toward the one side inthe axial direction of the swinging shaft.

In the present example, as illustrated in FIG. 2(a) and FIG. 2(b), therotating body 26 comprises a case member 35, and a bearing holder 36,and a holding member 37 that are detachably fixed to the case member 35.

The case member 35 constitutes the lower section of the rotating body26, has a thick disc shape, and is arranged so as to be coaxial with thereference axis α. The case member 35 has a bottomed holding recesssection 38 which is open to the upper side surface which is the surfaceopposite to the molding die 15. As illustrated in FIG. 2(b), the shapeof the holding recess section 38 as seen from above is rectangular whichextends in the radial direction about the reference axis α. Further, thecase member 35 has a through-hole 39 in a part of a section whichcorresponds to a bottom section of the holding recess section 38. Thisthrough-hole 39 is also provided in a state it extends in the samedirection as the extending direction of the holding recess section 38.

The bearing holder 36 is fitted inside one side half section in thelongitudinal direction (right half section in FIG. 2) without rattle. Onthe other hand, the holding member 37 is fitted inside the other halfsection in the longitudinal direction of the holding recess section 38(left half section in FIG. 2) without rattle.

The bearing holder 36 has an approximately square cylinder shape, and aretention hole 27 is provided inside the radial direction thereof. Thefirst inclined surface section 40 is provided at the end section on theother side (left side in FIG. 2(a)) in the longitudinal direction of theholding recess section 38 on the outer circumferential surface of thebearing holder 36. The first inclined surface section 40 is inclined ina direction toward the retention hole 27 in relation to the directionwhich is orthogonal to the reference axis α (the left-right direction inFIG. 2(a)) toward the side opposite to the molding die 15 (the upperside in FIG. 2(a) in relation to direction of the reference axis α (theup-down direction in FIG. 2(a)). In the present example, the firstinclined surface section 40 is inclined in the same direction at thesame angle as the retention hole 27.

The holding member 37 has an approximately rectangular parallelepipedshape, and the second inclined surface section 41 is provided at the endsection on the one side (the right side in FIG. 2(a)) in relation to thelongitudinal direction of the holding recess section 38 on the outercircumferential surface of the holding member 47. The second inclinedsurface section 41 is inclined in the same direction at the same angleas the first inclined surface section 40.

In this state, while the lower surface of the bearing holder 36 comes incontact with the bottom section of the holding recess section 38, thelower surface of the holding member 37 faces to the bottom section ofthe holding recess section 38 via a gap.

In the present example, for example, preload in the direction toward thebottom section side (the lower side in FIG. 2(a)) of the holding recesssection 38 is applied to the holding member 37 due to tightening forceof a holding bolt (not shown). Due to this, wedge effect occurs at theengagement section between the first inclined surface section 40 and thesecond inclined surface section 41 so that strict location control ofthe bearing holder 36 with respect to the holding recess section 38 isdone. Further, in this state, axial force is applied to the holding boltdue to elastic deformation of the holding member 37 so that occurrenceof loosening of the holding bolt by the vibration that occurs whenperforming orbital forging is effectively prevented.

Although illustration is omitted, as a further safety measure, it isalso possible to employ construction where the holding member 37 isprevented from rising upwards by pressing down the top surface of theholding member 37 by a lid member which is connected and fixed to thecase member 35 with bolts or the like.

In any case, in the present example, the bearing holder 36 and theholding member 37 are detachably fixed to the case member 35 based onattachment and detachment of the holding bolt or the lid member or thelike as described above.

In the present example, the end section on the other side in the axialdirection of the swinging shaft 13 is inserted into the retention hole27 of the bearing holder 36 through the through-hole 39 of the casemember 35.

Further, a member which prevents the swinging shaft 13 from movingtoward the one side in the axial direction with respect to the frame,that is, which prevents the connected body 23 of the molding die 15 andthe spherical seat with shaft 12 from moving toward the one side in theaxial direction of the swinging shaft 13 with respect to the frame, forexample, a thrust sliding bearing having a partially spherical slidingsurface, is not assembled in a portion of the swinging shaft 13 which islocated between the convex spherical seat 14 and the driving mechanism17 in the axial direction.

In the present example, the inclination angle θ, which is a swing angleof the molding die 15 when performing orbital forging, is set to be 15degrees or more and 30 degrees or less. In the present example, in spiteof such large inclination angle θ, space for placing a member such as athrust sliding bearing in the frame 10 is not required, because amechanism for preventing the swinging shaft 13 from moving toward theone side in the axial direction with respect to the frame 10 is providedat the connecting section of the driving mechanism 17 and the other endsection in the axial direction of the swinging shaft 13. Accordingly,reduction in size of the device and its manufacturing cost is achieved.

When forming a crimped portion 9 at the inner end section in the axialdirection of the hub body 6 by using the orbital forging device of thepresent example having such construction, as illustrated in FIG. 1, in astate where the hub body 6 before forming the crimped portion 9 andother parts of the hub unit bearing are assembled together, they aresupported by a support jig 18 which is provided at the top surface ofthe elevating base 11 in a state where the hub body 6 does not rattle inthe radial direction and the center axis of the hub body 6 is matched tothe reference axis α.

The elevating base 11 is lifted in this state, and as illustrated inFIG. 3(a), a part in the circumferential direction of the machiningsurface section 20 of the molding die 15 is pressed down to a part inthe circumferential direction of the inner end section in the axialdirection of the cylindrical section 8 which is provided at the innerend section in the axial direction of the hub body 6. In this state, therotating body 26 is made rotate around the reference axis α, and theconnected body 23 of the molding die 15 and the spherical seat withshaft 12 is made swing and rotate around the reference axis α, that is,based on the intersection point P of the reference axis α and the centeraxis ß of the connected body 23. For example, it is also possible toprovide a proximity sensor (not shown) to the orbital forging device andmeasure the distance between the part in the circumferential directionof the machining surface section 20 of the molding die and the part inthe circumferential direction at the inner end section in the axialdirection of the cylindrical section 8 which is provided at the innerend section in the axial direction of the hub body 6 by the proximitysensor, and at a stage of reaching a predetermined distance, that is, ina state where the molding die 15 and the cylindrical section 8 approachto each other but before in complete contact, initiate swinging androtation of the connected body 23.

When doing this, the connected body 23 of the molding die 15 and thespherical seat with shaft 12 rotate around the center axis ß of theconnected body 23 itself based on the friction force that acts on thecontact portion with the inner end section in the axial direction of thecylindrical section 8. Due to this, load toward outside in the axialdirection and outside in the radial direction is applied to a section inthe circumferential direction of the cylindrical section 8. Bycontinuously changing this section to which this load is applied in thecircumferential direction, as illustrated from FIG. 3(a) to FIG. 3(b) inorder, the inner end section in the axial direction of the cylindricalsection 8 is made gradually plastically deform so as to form the crimpedportion 9. Especially, due to such orbital forging, the swing angle ofthe molding die 15 (inclination angle θ) when forming the crimpedportion 9 is set to be 15 degrees or more and 30 degrees or less, it ispossible to suppress the maximum machining load when performing thisorbital forging. However, in the present invention, it is also possibleto set the inclination angle θ to be at an angle which is not within therange of 15 degrees or more and 30 degrees or less.

Further, this inclination angle θ is preferably at a constant angleduring the process of orbital forging. Especially, in a processillustrated in FIG. 5 for manufacturing a hub unit bearing using taperedrollers 5 a as rolling elements, the inclination angle θ is set to be 15degrees or more and 30 degrees or less and initiate orbital forgingusing the proximity sensor, and by maintaining the inclination angle θduring the process of orbital forging at a constant angle, it ispossible to suppress machining load for forming the crimped portion 9and make the inner ring 7 prevent the inner ring raceway 4 b on theinside in the axial direction which is provided on the outercircumferential surface from plastically deforming as it bulges.

In the orbital forging device of the present example, the end section onthe other side in the axial direction of the swinging shaft 13 issupported to the driving mechanism 17 in a state where the movementtoward the one side in the axial direction is prevented. Therefore, dueto this supporting section, it is prevented that the connected body 23of the molding die 15 and the spherical seat with shaft 12 move towardthe one side in the axial direction of the swinging shaft 13 withrespect to the frame 10 (drop downwards in FIG. 1). Further, a memberfor preventing the swinging shaft 13 from moving toward the one side inthe axial direction with respect to the frame 10, for example, a thrustsliding bearing having a partially spherical sliding surface, is notassembled in a portion of the swinging shaft 13 which is located betweenthe convex spherical seat 14 and the driving mechanism 17 in the axialdirection. Therefore, it is possible to reduce the size andmanufacturing cost of the orbital forging device by that amount.

Further, in the present example, the bearing holder 36 and the holdingmember 37 are detachably fixed to the case member 35. Therefore, bychanging the bearing holder 36 and the holding member 37 to change theinclination angle of the retention hole 27, it is possible to change theswing angle of the molding die 15 (inclination angle θ) in a wide range.Therefore, it is possible to select an optimal swing angle θ inaccordance with the type of a work piece (for example, hub body 6). Theinsertion position of the swinging shaft 13 with respect to thethrough-hole 39 of the case member 35 changes according to the swingangle of the molding die 15 (inclination angle θ).

EXPLANATION OF REFERENCE NUMBERS

-   1 Outer ring-   2 Hub-   3 a, 3 b Outer ring raceway-   4 a, 4 b Inner ring raceway-   5 Balls-   5 a Tapered rollers-   6 Hub body-   7 Inner ring-   8 Cylindrical section-   9 Crimped portion-   10 Frame-   11 Elevating base-   12 Spherical seat with shaft-   13 Swinging shaft-   14 Convex spherical seat-   15 Molding die-   16 Concave spherical seat-   17 Driving mechanism-   18 Support jig-   19 Convex spherical surface section-   20 Machining surface section-   21 Insertion hole-   22 Concave spherical surface section-   23 Connected body-   24 Stepped hole-   25 Bearing device-   26 Rotating body-   27 Retention hole-   28 Rolling bearing-   29 Outer ring-   30 Inner ring-   31 Spherical rollers-   32 Stepped surface-   33 Male screw section-   34 Nut-   35 Case member-   36 Bearing holder-   37 Holding member-   38 Holding recess-   39 Through-hole-   40 First inclined surface section-   41 Second inclined surface section-   42 Thrust sliding bearing

What is claimed is:
 1. A bearing support, comprising: a case memberhaving a holding recess, the holding recess having an inner peripheralsurface and a bottom section; a bearing holder having an outerperipheral surface and a retention hole inside which a bearing isfitted; and a holding member arranged between the inner peripheralsurface of the holding recess and the outer peripheral surface of thebearing holder, to which preload in a direction toward the bottomsection of the holding recess is applied; wherein the holding memberregulates a position of the bearing holder with respect to the holdingrecess due to wedge effect.
 2. The bearing support according to claim 1,wherein the bearing holder has a first inclined surface section providedat a portion of the outer peripheral surface, the first inclined surfacesection inclined in a direction toward the inner peripheral surface ofthe holding recess as going away from the bottom section in relation toa depth direction of the holding recess, and the holding member has anouter peripheral surface and a second inclined surface section providedat a portion of the outer peripheral surface of the holding member andcoming in surface contact with the first inclined surface section. 3.The bearing support according to claim 1, wherein the bearing holder isin contact with the bottom section of the holding recess, and theholding member faces to the bottom section of the holding recess via agap.
 4. The bearing support according to claim 1, wherein the casemember has a through-hole in part of a portion corresponding to thebottom section of the holding recess.
 5. The bearing support accordingto claim 1, wherein the holding recess has a rectangular shape as seenfrom a depth direction of the holding recess, the bearing holder isfitted inside one side half in a longitudinal direction of the holdingrecess, and the holding member is fitted inside other side half in thelongitudinal direction of the holding recess.
 6. The bearing supportaccording to claim 1, wherein a holding bolt is provided to apply thepreload to the holding member.
 7. The bearing support according to claim1, wherein a lid member is connected and fixed to the case member topress down a surface of the holding member on an opposite side to thebottom section of the holding recess.
 8. An orbital forging device,comprising: a frame having a reference axis, a swinging shaft having acenter axis, an end section on one side in an axial direction thereof,and an end on the other side in the axial direction, the center axisarranged to be inclined with respect to the reference axis, a convexspherical seat having one side section in the axial direction of theswinging shaft, the other side section in the axial direction of theswinging shaft, and a convex spherical surface section provided on theother side section, the convex spherical seat connected to the endsection on the one side in the axial direction of the swinging shaft tobe coaxial with the swinging shaft, a molding die comprising a machiningsurface section in a side surface on the one side in the axial directionof the swinging shaft, the molding die connected to the side surface onthe one side of the convex spherical seat to be coaxial with theswinging shaft, a concave spherical seat fixed to the frame andcomprising a concave spherical surface section which spherically engageswith the convex spherical surface section and an insertion hole to whichthe swinging shaft is inserted, and a driving mechanism assembled in theframe and connected to the end section on the other side in the axialdirection of the swinging shaft to provide driving force to the endsection on the other side in the axial direction of the swinging shaftfor rotating a connected body of the swinging shaft, the convexspherical seat, and the molding die around the reference axis, whereinthe driving mechanism comprises the bearing support according to claim1, the bearing support supported to the frame rotatably around thereference axis of the frame, the end section on the other side in theaxial direction of the swinging shaft is inserted through the retentionhole of the bearing holder, the bearing is arranged between theretention hole and the end section on the other side in the axialdirection of the swinging shaft, and the end section on the other sidein the axial direction of the swinging shaft is supported with respectto the driving mechanism in a state where a movement thereof toward theone side in the axial direction is prevented by the bearing.
 9. Theorbital forging device according to claim 8, wherein the rolling bearingcomprises an outer ring, an inner ring, and a plurality of rollingelements provided between the outer ring and the inner ring, to supportaxial load that acts on between the outer ring and the inner ring, andthe inner ring is externally fitted onto the end section on the otherside in the axial direction of the swinging shaft in a state where adisplacement thereof toward the other side in the axial direction of theswinging shaft is prevented, and the outer ring is fitted inside theretention hole in a state where a displacement thereof toward the oneside in the axial direction of the swinging shaft is prevented.
 10. Theorbital forging device according to claim 8, wherein the case member hasa through-hole in part of a portion corresponding to the bottom sectionof the holding recess, and the end section on the other side in theaxial direction of the swinging shaft is inserted to the retention holeand the through-hole.
 11. The orbital forging device according to claim8, wherein the inclination angle of the center axis of swinging shaftwith respect to the reference axis is 15 degrees or more and 30 degreesor less.